The present invention relates to a process for producing multilayer particles (typically a core layer covered with an upper layer), typically by laser pyrolysis. It also relates to an associated device.
Such a process enables a user for example to manufacture submicron particles of silicon or silicon carbide, each covered with a layer of aluminium or aluminium oxide.
Processes for producing a material are known in which the raw material used is a mixture of two powders, at least one of which is characterized by an average grain size in the nanometric range:                a powder of particles of a first type, for example of silicon carbide, and        a powder of particles of a second type, which are particles of aluminium or aluminium oxide.        
Then the whole is heated to a moderate temperature, optionally under pressure, without bringing it to the melting temperature (“sintering” process), in order to obtain a dense nanostructured material.
There may be problems of inhomogeneity between the silicon carbide and the aluminium oxide or the aluminium in the material obtained, in particular arising from difficulties in mixing two powders, at least one of which is a nanometric powder. These difficulties arise from the agglomeration forces, which are greater in the case of nanometric powders, and which make it difficult to obtain a material of homogeneous microstructure or nanostructure when a powder of nanometric size is used.
Moreover, there may be problems of binding or of chemical compatibility between the particles of the two powders, making it necessary to carry out chemical or thermal post-treatments on the powders before using them.
The aim of the invention is to propose:                a novel raw material,        a process for producing this raw material,        various uses of this raw material.        